In the mid-1990s a product was developed that was a significant advance over the existing technology for room darkener fabrics. Using a system of inherently flame resistant yarns, a fabric was woven which had three layers of fiber, each layer interlaced between warp and filling, incorporating a natural warp with a black filling. The black filling was package dyed yarn. The weave used produced a fabric that has about half the warp yarn weaving on the face and about half the warp yarn weaving on the back, with about 80% of the black filling in the middle layer, bound with the warp yarns. The final fabric has a face and back each made up of approximately 90% white yarn and 10% black filling yarn with the balance of the black filling yarn forming the middle layer. The fabric uses flame resistant yarns throughout and is capable of passing the necessary fire tests, namely those provided by fire code NFPA-701-96.
While the prior art fabric described above has been very successful, it does have several drawbacks. The first is that while it does have excellent room darkening properties, there are still many circumstances where well over 2% of the visible light is transmitted. Thus while the light level that it provides is low, it may not be completely dark in a room using the fabric as a room darkener should there be a number of windows with the sun shining directly on the windows. Also the fabric can only be produced in prepared-for-print form (that is scoured and heat set) because the black dye bleeds during the high temperature used in dyeing, and contaminates the color of the white warp yarn.
According to the present invention, by making in hindsight minor modifications to the prior art fabric, its performance has been enhanced dramatically, and its versatility has been enhanced, while its cost is decreased.
According to the present invention, a fabric is produced that is substantially the same as the prior art fabric except that instead of using all flame resistant yarns, the filling yarn is non-flame resistant yarn that is solution dyed black. Despite the fact that the filling yarns are non-flame resistant because of the fabric construction it passes fire code NFPA-701-96, which is necessary for it to be appropriately used as a room darkener fabric in the hospitality and health care market.
By making a simple, in hindsight, change in the type of filling yarn used, and solution dyeing the filling yarn, dramatic advantages have been achieved. The first functional advantage is that the fabric according to the invention is much more opaque than the prior art fabric. The fabric according to the present invention transmits less than 2% of the visible light, and less than 2% of the infrared light, in all circumstances for which it has been tested, and most of the time less than 1 % of the light; that means it blocks at least 98% of the light, and typically more than 99% of the light. In tests comparing the fabric according to the invention with the prior art fabric, under exactly the same circumstances, the amount of visible light transmitted using the prior art fabric ranged from 1.95% to 7.23%, whereas for the fabric according to the invention the amount of visible light transmitted ranged between 0.46% and 1.27%, in some circumstances literally making a perceived difference of between xe2x80x9cnightxe2x80x9d and xe2x80x9cdayxe2x80x9d.
Also the fabric according to the invention can be produced in prepared-for-print form where it is scoured and heat set and also in dyed form, dyeing the white warp yarns without the bleeding or running of the black filling yarns during the high temperature used in the dyeing process. This can provide much more aesthetic and versatile fabrics.
Further, despite the fact that a non-flame resistant polyester filling yarn is utilized (which yarn is usually less expensive and more versatile than comparable flame resistant yarns) the fabric still obtains results that have passed NFPA-701-96. Thus without commercially significant change in the flame resistance properties a much more functional and versatile fabric is produced according to the invention.
The following table indicates the results of comparative testing between the fabric according to the present invention with non-flame resistant solution dyed black polyester filling yarns, and the fabric of the prior art which is the same as the fabric of the invention only with flame resistant packaged dyed polyester filling yarns. In the table the fabric according to the invention has code number 3187, and the prior art fabric has code number 37095.
Thus, the fabric according to the present invention blocks at least 98%, and typically more than 99%, of the visible and infrared light waves; a decrease of about 300-500% in the amount of light transmitted compared to the prior art.